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Biomedical subjects

J Marco

Publications and source records attributed to J Marco.

At least 307 records · Page 17Linked to original sources
PubMedDate not supplied

Vestibulo-ocular reflexes in peripheral labyrinthine lesions: III. Bilateral dysfunction.

Measurements were made of the lesion-induced changes in vestibulo-ocular reflexes (VOR) to rotatory stimuli in a group of patients with bilateral peripheral labyrinthine lesions. All the patients had caloric responses that were below the confidence levels used for normal responses in our laboratory. Responses to rotatory stimuli were greatly decreased or absent at low frequencies of stimulation, but present to a much greater degree at the higher frequencies. Phase measurements showed an increase in relationship to the velocity of the stimulus; there was a corresponding shortening of the time constant as obtained from impulse response measurements. A parametric study indicated that the changes in the responses can be described by a decrease in the sensitivity coefficient and in the basic time constant of a simplified pendulum model equation of vestibular function. A theoretical analysis of the data using a new model for the organization of the vestibular pathways indicated that the preservation of the high-frequency responses was the result of adaptive changes brought about in the central vestibular pathways and/or changes in the receptor-neuron transduction characteristics. Thus, despite the almost complete absence of any caloric response, the vestibular system reflexes remained adequate to maintain gaze during normal head movements.

Adult↗
PubMedDate not supplied

Ultrastructural study of the human utricular macula and vestibular nerve in meniére's disease.

The authors have carried out an ultrastructural study of the human utricular macula and the vestibular nerve in the internal acoustic meatus of four patients suffering from Meniere's disease. They confirm the presence of degenerative alterations in the utricular sensory epithelium. The nervous fibers situated in the supporting connective tissue of the neuro-epithelium showed modifications in the Schwann cell cytoplasm and in the arrangement of the myelin sheaths. The same alterations appear in the vestibular nerve in the internal acoustic meatus in 2 of our cases. In the other 2, the vestibular nerve was formed by a granular matrix with several myelin figures in the proximity of possible Schwann cell nucleus debris.

Adult↗
PubMedDate not supplied

Macroscopic and ultrastructural findings in some diseases of the facial nerve.

The authors describe the findings observed in: 10 cases of Bell's palsy, 1 case of traumatic facial paralysis, 1 case of congenital facial paralysis, and 1 case of Melkersson-Rosenthal syndrome. The chorda tympani nerve of these patients was studied, employing the electron microscope, comparing it with that of 5 patients having otosclerosis. Our ultrastructural findings appear to confirm that the chorda tympani nerve presents a similar degenerative behaviour in those diseases studied by us. The degenerative stages range from a lesser to greater degree in the following order: Bell's palsy, traumatic facial paralysis, congenital facial paralysis, Melkersson-Rosenthal syndrome.

Adolescent↗
PubMedDate not supplied

Cis-diaminedichloro platinum ototoxicity. An experimental study.

Four groups of guinea pigs received different doses of cis-platinum. SEM and TEM showed a direct relation between the dose and the damage. The first row of OHC is the first one to be damaged. The IHC are more resistant than the OHC. The pattern of destruction is similar to the one produced by the aminoglucoside antibiotics.

Animals↗
PubMedDate not supplied

[First spontaneous epileptic crisis in childhood: risk of relapse and prognostic factors].

INTRODUCTION: Knowing the risk of relapse after a first epileptic crisis is important because of its repercussion on the patient. The prognosis is uncertain in some types of crisis. OBJECTIVE: To find the probability of relapse and risk factors after a first spontaneous epileptic convulsive crisis, focal or generalized, occurring in childhood or adolescence. PATIENTS AND METHODS: We followed a cohort of 139 patients from the Health District of Hospital General of Albacete who had had this type of crisis before the age of 14. Patients with acute symptomatic, febrile or neonatal convulsions were excluded. The probability of relapse was calculated using Kaplan-Meier curves, and multivariate analysis was carried out. RESULTS: The probability of relapse 24 months after the first epileptic crisis is 70% and after 76 months is 75%. Of a series of variables analyzed, the only one associated with increased risk of relapse was the 'aetiology': the relative risk of relapse in patients with previous symptomatic aetiology is 2.1 as compared with those of idiopathic aetiology (p < 0.001). CONCLUSIONS: Patients who have had a first focal or generalized convulsive epileptic crisis in childhood have a 75% probability of developing epilepsy over the subsequent 6 years; this risk is greater in those with a previous symptomatic aetiology, so this should be taken into account when deciding on the treatment of these patients.

Age Factors↗
PubMedDate not supplied

[Report of a case with skin lesions and calciphylaxis].

Calciphylaxis is an unusual complication of chronic renal failure associated with increased morbidity and mortality. This presentation is a clinical case describing a patient parathyreidectomized in 1997, followed by the condition was clinically suspected and then confirmed by skin biopsy. PTHi levels above 400 pg/ml together with scintigraphic images suggesting parathyroid nodules resulted in the decision to try a new surgical procedure, which yielded two nodules of thyroideal tissue. After the surgery and in spite of this pathology result, the patient recovered completely from her symptoms. This corroborates the theory that the etiology of calciphylaxis is multifactorial, acquiring special relevance the use of calcium-containing phosphathe binders (representing a high risk of hypercalcemia) in the treatment of Chronic Renal Disease.

Calciphylaxis↗
PubMedDate not supplied

[Late postoperative apnea in a premature newborn infant].

We report the case of a premature newborn child (36 weeks) who was operated on a teratoma of the sacrum when he was 12 days old and weighed 2,950 g. The patient presented a late postoperative apnea 17 hours after anesthesia. The anesthetic technique consisted of lumbar epidural blockade with 0.33% bupivacaine at a dose of 2.25 ml and superficial inhalation anesthesia with 0.5% isoflurane. Relaxing muscular agents used in this case were succinylcholine (3 mg) for orotracheal intubation and pancuronium bromide (0.3 mg) for maintaining the anesthetic level. The immediate postoperative phase was uneventful but 17 hours after surgery the patient presented apnea, bradycardia (40 beats/min), and marked cyanosis requiring assisted ventilation with bag and mask during 3 min and initial cardiac massage. Recovery of heart rate was immediate and recovery of ventilation was progressive. The patient was treated with caffeine during one week and no relapses occurred. Pneumocardiographic recordings obtained later on revealed sporadic short lasting episodes of apnea (shorter than 15 s) sometimes associated with bradycardia (40 beats/min lower than baseline). There were no apparent intercurrent or precipitating factors for this apnea. We believe that the present clinical picture corresponds to a late postoperative apnea of unknown origin which required reanimation measures and that until present, there are no reported complications of the anesthetic technique that can explain this episode.

Anesthesia, Epidural↗
PubMedDate not supplied

[A neuroanatomical study of the vestibular efferent system, III: the origin and pathway of the axons].

We have studied the vestibular efferent fibers pathway, after scratching the peripheral vestibular receptors and horseradish peroxidase injection, and TMB or DAB processing. We have proved the existence of a differentiated bundle in the main vestibular pathway, this bundle crosses the areas where the efferent somas have been situated, some of this fibers have been seen crossing the midline. It has not been possible to connect the efferent somas with the fibers.

Animals↗
PubMedDate not supplied

[Neuroanatomic study of the efferent vestibular system I: distribution of the somas in the brain stem. A qualitative study].

EVN are studied in the chinchilla by means of HRP tract tracer, using TMB and DAB as chromagen. Three groups of EVN somas have been identified within the brainstem; located in the proximity of the vestibular nuclei (I), the facial nerve genu (II) and the abducens nucleus (III). The extension, localization and anatomical relations have been determined.

Animals↗